Bridles

ABSTRACT

THE INVENTION CONCERNS A DEVICE WHICH PLACES TENSION ON A METAL STRIP BY PULLING THE LATTER BY MEANS OF PULLING ROLLS OF A PULLING BRIDLE THROUGH DRAG ROLLS OF A DRAG BRIDLE, EACH OF THE PULLING AND DRAG ROLLS BEING COUPLED TO A FOLLOWING ROLL BY MEANS OF A DIFFERENTIAL, AND ALL ROLLS BEING DRIVEN BY A COMMON MOTOR.

1971 P. A. DEFONTENAY 3,526,737

BRIDLES Filed Oct. 29. 1969 swam 1M PAUL. A DEFONTENAY United States Patent 3,626,737 BRIDLES Paul A. Defontenay, Bourg-la-Reine, France, assignor to Wean Industries, Inc., Youngstown, Ohio Filed Oct. 29, 1969, Ser. No. 872,214 Claims priority, application France, Dec. 27, 1968, 181,159 Int. Cl. B21b 39/08 US. Cl. 72-205 Claims ABSTRACT OF THE DISCLOSURE The invention concerns a device which places tension on a metal strip by pulling the latter by means of pulling rolls of a pulling bridle through drag rolls of a drag bridle, each of the pulling and drag rolls being coupled to a following roll by means of a differential, and all rolls being driven by a common motor.

BACKGROUND AND SUMMARY Tensioning of metal strip is effected by machines called bridles, and the tension is obtained by means of a series of pulling rolls which continuously pull the strip through another series of drag rolls.

The elongation of the strip material under tension requires, in order to avoid slippage on the rolls and thus loss of tension, that the circumferential velocities of the respective rolls be related to the elongation of the strip material. This requirement has led to the use of kinematic and geometric means, such as predetermination of the speed of each of the rolls, and adjustment of their diameters. In spite of this, the slippage has not been completely avoided and has necessitated that each bridle be designed for a specific gauge of metal strip.

My invention provides a tension unit which avoids slippage and which can be used with any strip material of any gauge, with simultaneous control of the torque at each roll of the bridles.

DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, the series of rolls 1, 2, 3 and 4 constitutes what may be termed a drag bridle, while the series of rolls 5, 6, 7 and 8 constitutes the pulling bridle, to create a tension on the portion of the strip S therebetween. Between the two bridles, a pair of rolls is illustrated, and

these rolls may illustrate a leveler P, or the rolls of any ice other suitable apparatus, such as a coating machine, controlled impression apparatus, or the like. The number of rolls in the drag and pulling bridles may be varied and their diameters need not necessarily be equal.

As shown in FIG. 1, a metal strip S for example, is pulled at a velocity V under a tension t by the roll 1. The strip may be supplied in any suitable manner, such as from an uncoiler reel (not shown). The strip leaves the roll 1 after a predetermined number of degrees of wrap therearound and then reaches the roll 2, and in the same way successively passes through all of the rolls up to the last one from whence it is accumulated by any suitable device (not shown).

According to my invention, and as particularly shown in FIG. 2, each pair of adjoining rolls in the groups of rolls 1 through 4 and 5 through '8 is mechanically linked together by a differential 9. Each differential comprises a case 10 which turns free on its shaft 11 and has satellite sprockets 12 and 13 linked together on a shaft which is supported by the respective case 10 for free rotation with respect thereto. The satellite gears 12 and 13 respectively mesh with planetary gears 14 and 15, the gear 14 being fixed to the shaft 11 while the gear 15 is coaxial with but rotatable relative to the shaft 11. Roll 1 is linked by a positive transmission, such as a chain 1a or the like, to the planetary gear 15 of roll 2.

Each pair of two dilferentials 9 receives its movement from, another differential 16, driven in turn by a motor 17 through a transmission 18, such as a chain or belt, and a shaft 19. A differential 20 is mounted on shaft 19, the case of this differential being connected by bevel gearing 20a to a speed variator 21. The speed variator 21 is driven from the shaft 19 by bevel gearing 21a, a servo-motor 22 providing for control of the speed variator.

Two similar differentials 23 and 24 are disposed in axial alignment with the shaft 19, each having a case which, under certain conditions, may be stopped or free to turn, a brake 25 and a stop 26 providing for control of the respective case. The motor 17 and transmission 18 may be of the type to drive the shaft 19 at only one speed, or at several constant speeds, or at infinitely variable speeds, and suitable standard controls (not shown) may be used to effect such speed control.

With reference to FIG. 1, the strip S enters the roll 1 under a tension 1 and will leave such roll under a tension T which is calculated by the formula T=te The tension in the strip has thus been increased from the value t to the value T, by limitation of slippage conditioned by the value of the coetficient of friction f on one hand and the value of the angle of wrap a on the other hand, a being equal to 1ra/ with a the angle of wrap in degrees, and e equal to 2.71828 (the base of natural logarithms). The two tensions correspond to two different torques on each of the rolls 1 and 2 (or succeeding pair of rolls) having the following value: torque on roll 1: (T-t)r, and torque on roll 2=(TT)r, with r being the radius of the rolls.

It is pointed out that as far as the value of the coefficient of friction f is concerned, this is dependent upon the type of material of the strip S on one hand, and the material constituting the rolls on the other hand, .and

A principal object of my invention is to eliminate or at least effectively reduce the slippage between the strip and rolls, and to enable the apparatus to be satisfactory for operation on strips of various metalurgical properties and various thicknesses, and this is effected by driving each pair of rolls of each series of two groups by the differentials herein disclosed.

In fact, in my improved system, case of each differential 9 will transmit to each of the pair of rolls through the satellite and planetary gears a rotation such as roll 1, for example, may absorb the strip S to a velocity V under a tension 2, and roll 2, in this example, will receive the strip S under a tension T with a velocity V1 which is slightly higher than V due to elongation of the strip. The reason of the creation of these two different velocities V and V1 as a function of strip elongation, and thus tension, is derived from the kinematic of the differential itself in which two turning elements, the planetary gears, may under external circumstances, modify in consequence to the velocity which is given to them by a third turning element, namely, the case. Furthermore, it is known that the system of active and reactive forces is in equilibrium when passing through a close loop, such as the rolls 1 and 2.

The choice in each of the differentials of its internal gearing, the ratio of which may have a value superior or inferior to 1, and realization of a pre-determined ratio for external transmission by chain, is shown as tension as increased from roll 1 to roll 5, and decreased from roll 5 to roll 8, for example. Thus, another principle object of my invention is the creation of a predetermined elongation in the strip and comes about by use in the main drive of a differential controlled by the speed-variator 21, the latter being under control of the servo-motor 22.

In this respect, it is pointed out that the shaft 19 creates on the axially aligned shaft 27 a rotation having a value depending both from the rotation of shaft 19 and the rotation of the case of the differential 20. If it is assumed that this case does not turn, the rotative relationship between the shafts 19 and 27 is defined by the internal gearing of the differential 20. However, if the case should turn, the rotative relationship between the two shafts 19 and 27 will in fact also be dependant on this rotation of the case.

Considering that the case of the differential 20 is driven by the exit end of the speed variator 21, the entry end of which is driven by the shaft 19, it will be possible to obtain slight modifications of the rotation of shaft 19 in relation to the rotation of shaft 27. This means that it will be possible to create on roll 4 of the drag bridle a slight decrease in speed as compared to the speed of the roll 5 of the pulling bridle and thus produce a certain elongation of the strip S, and the speed variator 21 provides for adjustment of the elongation.

A further principal object of my invention is permanent control of the torques on the rolls and this is provided by the use in the main drive of the two differentials 23 and 24, the cases of each of which may be immobilized under certain conditions. In this respect, the case of each of the differentials 23 and 24 is linked to a brake 25 turning free on the respective shafts 19 and 27, and the brakes are prevented from turning by means of a stop 26 which has adjustable action. The braking action of the differential cases 23, 24 prevents the entire system from freewheeling, so that torque may be transmitted by shafts 28 and 29. The stop 26 is a conventional load measuring sys tem to read the torque being transmitted by the shaft. This same stop is so arranged as to release or slip if torque ratings of the system are exceeded and may also be released by the operator when threading strip through the apparatus, or for other reasons.

The transmissions of the rotations and the torques from the shafts 19 and 27 to shafts 28 and 29 is realized through the planetary and satellite gears in the respective transmissions 23 and 24, and the reaction to the transmission of rotation and torque is through the respective case brought about by the brake 25 and stop 26 Therefore, it will be seen that if the system is normally in equilibrium it will not remain so as soon as the resistive torque on the shafts 28 or 29 will overcome the adjusted value of the respective stop 26, and therefore the case of the respective differential 23, 24 will rotate by slipping in its brake 25. The motor 17 may be stopped by means of an electrical contact (not shown). It is pointed out that each of the brakes 25 may be set free by another drive (not shown) to insure release of the clutch between the shafts 28 and 29.

I claim:

1. A bridle for metal strip, comprising two rolls each having a driving shaft, the strip being adapted to be wrapped around a portion of the periphery of one roll and then around a portion of the periphery of the other roll, a differential coupling said rolls, comprising a case revolvable about the shaft of one of said rolls and drivingly connected to the shaft of the other roll through planetary gearing within said case, and a motor for rotating said differential case.

2. The construction according to claim 1 wherein a second differential is interposed in the line of drive between said motor and said first differential case, said second differential comprising a rotatable case, and planetary gearing within the same, and a speed variator acting on the case of said second differential for varying the drive.

3. A bridle apparatus, comprising two rolls forming a drag bridle and two rolls forming a pulling bridle for pulling metal strip through said drag bridle, incoming strip being adapted to be wrapped around a portion of the periphery of one roll of said drag bridle and then around a portion of the periphery of the other roll of said drag bridle, and thereafter passing to and wrapped around a portion of the periphery of one roll of said pulling bridle and then around a portion of the periphery of the other roll of said pulling bridle, a first differential, including a rotatable case and planetary gearing in said case, for coupling the rolls of said drag bridle, and a second differential, including a rotatable case and planetary gearing in said case, for coupling the rolls of said pulling bridle, and a common motor for driving the rolls of said drag and pulling bridles through their respective differentials.

4. The construction according to claim 3 and further including a third differential, including a rotatable case and planetary gearing within said case, for coupling said drive motor and first differential, and a fourth differential, including a rotatable case and planetary gearing within said case, for coupling said drive motor and said second differential.

5. The construction according to claim 4 and further including brake means operationally related to the cases of said third and fourth differentials for controlling rotation of the same.

6. The construction according to claim 5 and further including a fifth differential, including a rotatable case and planetary gearing within said case, and a speed variator including a drive connection to the case of said fifth differential.

7. The construction according to claim 6 wherein said speed variator is driven by said drive motor.

8. Bridle apparatus for metal strip, comprising four successively adjoining rolls with their rotational axes in parallel relation, the metal strip being adapted to be wrapped successively around portions of said rolls, a first differential, including a rotatable case and planetary gearing in said case, effecting driving relation between a first pair of adjoining rolls, and a second differential, including a rotatable case and planetary gearing in said case, effecting driving relation between the second pair of adjoining rolls, and a third third differential, including a rotatable case and planetary gearing in said case, effecting driving relation between said first and second differentials, and a motor References Cited for driving said third differential.

9. The construction according to claim 8 and further in- UNITED STATES PATENTS cluding a fourth differential, including a rotatable case and 3,427,848 2/1969 F 72 205 planetary gearing within said case, interposed in the line 5 2,219,665 10/1940 slmon s 72-205 of drive between said third differential and said motor, 3320327 5/1967 Rumnch 72249 X and a speed variator including a drive connection to the FOREIGN PATENTS case of said fourth differential.

10. The construction according to claim 9 and further 212206 4/1967 Sweden 72205 including a fifth differential, including a rotatable case and 10 MILTON S. MEHR, Primary Examiner planetary gearing Within said case, interposed in the line of drive between said fourth differential and said third differential, and brake means adapted to act on the case of 72249 said fifth differential. 

